Two-stage oil well casing cementing with upper and lower stationary jets for secondary stage



Nov. 6, 1962 E. M. KIPP 3,052,235

TWO-STAGE OIL WELL- CASING CEMENTING WITH UPPER AND LOWER STATIONARY JETS FOR SECONDARY STAGE 3 Filed Dec. 2. 1959 2 Sheets-Sheet 1 INVENTOR EARL M. KIPP 'r'ro N E M. KIPP Nov. 6, 1962 TWO-STAGE OIL WELL CASING CEMENTING WITH UP? AND LOWER STATIONARY JETS FOR SECONDARY STAGE Filed Dec. 2, 1959 2 Sheets-Sheet 2 FIG. 3

FIG.5

R o T N E V N EARL M. K/PP ATTORNEYS United States Patent Ofiice 3,062,285 Patented Nov. 6, 1962 3,062,285 TWO-STAGE OIL WELL CASING CEMENTING WITH UPPER AND LOWER STATIONARY JETS FOR SECONDARY STAGE Earl M. Kipp, Piedmont, Calif, assignor to California Research Corporation, San Francisco, Calif, a corporation of Delaware Filed Dec. 2, 1959, Ser. No. 856,840 4 Claims. (Cl. 166-22) This invention relates to well cementing and more particularly it relates to methods and apparatus in cementing operations wherein a stream of cement is forced against the borehole Wall above and below a producing formation to remove filter cake, mud and other accumulations, thereby making a better bonding surface available between the cement and the borehole wall.

It is often desirable in oil well completion work to isolate a producing formation from the underlying and overlying strata. This is particularly desirable when these strata give off water which is likely to drain along the borehole wall in to the producing zone. The usual method of preventing this drainage is to place an amount of cement between the casing and the borehole wall from the bottom of the well to a point somewhere above the producing formation. This cementing operation is usually accomplished by pumping cement through the casing out into the bottom of the well and then forcing it up between the well bore wall and the outside of the casing. A serious problem is encountered, however, when the borehole wall is covered with a layer of filter cake or dehydrated mud. The cement will set without displacing the mud and channeling will result wherein water will flow through the channels left by the mud and into the producing formation. The removal of this filter cake and mud has been attempted by mechanical scrapers and chem ical solvents. Neither of these methods has met with any particular degree of success. A method as taught by U.S. Patents 2,811,206 and 2,811,208, wherein cement is forced into the void between the casing and the borehole wall in the conventional manner and then flow diverted to a ring of jet ports in the casing where a stream of cement is forced against the borehole wall to peel the mud from the wall, has met with a greater degree of success. However, these patents teach the jetting process over only a limited vertical area at one time. Since, as noted above, it is necessary to isolate the producing formation from above and below, it becomes evident that the casing must be moved to accomplish the removal of the filter cake both above and below the producing formation. This is undesirable because of the obvious difficulty of repeated moves of the casing. This is particularly true in deep wells wherein relatively thin producing zones are located because of the difficulty of positioning the casing and the very present possibility of sticking the casing while attempting the move.

It is an object of the present invention to obviate the necessity of moving the casing in cementing operations while obtaining the simultaneous removal of the borehole wall debris above and below the desired producing formation in order that a Watertight seal of cement may be there effected. It is a further object of the invention to provide a better bonding surface between the cement and borehole wall by simultaneously peeling mud and filter cake from the borehole wall above and below the producing formation. It is a further object of this invention to provide apparatus to abrade filter cake and mud from the Wall of a borehole, said apparatus to be incorporated in the casing and cemented in place in the borehole with said casing.

The novel and inventive features of the invention, both as to method and operation, and further objects and advantages of the invention will become apparent from the following detailed description when read in connection with the accompanying drawings, which are incorporated herein and made a part of this disclosure.

In the drawings:

FIGURE 1 is a vertical section of an embodiment of the invention located in a borehole in combination with a conventional cement float shoe wherein cement slurry is being pumped through the casing, the hollow member and the ball valve into the void between the borehole wall and the casing.

FIGURE 2 is a vertical section of the same embodiment of the invention located in a borehole wherein a cement plug has seated in the beveled face of the cement collar and opened the port means on the hollow member to the cement slurry, thus causing jetting action of the annular chambers.

FIGURE 3 is a section view of section 33 in FIG- URE 1.

FIGURE 4 is a vertical section of an alternative embodiment of the invention located in a borehole wherein the restricted passageway means and the design of the jet ports have been altered.

FIGURE 5 is a sectional view of section 5-5 in FIG- URE 4.

In a preferred embodiment of the invention, there is provided in combination with the casing pipe and conventional float shoe an elongated hollow member that can be interconnected with and serve as a portion of the casing. This hollow elongated member may be either a section of the casing which is used in casing the borehole whereon the other elements of the apparatus are attached, or the hollow elongated member may be a section of pipe on which the other elements of the apparatus are attached similar to the casing pipe which can be fitted into the easing string. Vertically spaced apart on the periphery of this hollow member are a pair of tubular members so connected to the hollow member as to form annular chambers. The vertical spacing is dependent on the thickness of the formation which is to be isolated; one annular chamber spaced to provide jetting action above the formation, the other annular chamber spaced to provide jetting action below the formation. A plurality of jet ports are spaced around the circumference of the annular chambers. These jet ports may take a variety of sizes and may be spaced at different intervals on the circumference. In the preferred embodiment the jets should be positioned so that the resulting spray of cement slurry strikes the well bore wall in such a manner as to give a pronounced scournig effect. interconnecting the annular chambers with port means on the hollow member are a plurality of restricted passageways. These passageways could take the form of sections of small-diameter pipe which had been divided into halves along their long axis and subsequently attached to the circumference of the hollow member. The port means in the hollow member are located approximately half way between the annular chambers so as to give approximately even flow to both chambers. Inside the hollow member, spaced near the port means, is a unit which is capable of converting from cement flow through the casing to cement flow through the port means located in the side of the tubular members. This device, which is known in the art as a cement collar, is typified by the device described in the Eadie Patent No. 2,811,208.

A typical method of operation involves determining the vertical increment that is to be sealed off and the depth of this increment from the surface of the earth. The apparatus is then attached to the casing at the appropriate position and hung in the borehole as a part of the casing. A typical float shoe containing a ball valve assembly is attached to the lower end of the casing.

Cement slurry is then pumped down the interior of the casing through the ball valve into the bottom of the borehole. As the amount of cement slurry increases, it begins to fill up the opening between the outside of the casing and the wall of the borehole. Sutficient cement slurry is pumped in this manner until the annular space between the casing and the well bore wall is filled to a predetermined level which is generally located somewhere above the top of the producing formation which is to be isolated. Since the cement collar is covering the port means in the hollow member of the apparatus, the hollow member will function as a part of the casing and cement slurry will flow through it and will not flow through the port means or clog the port means. When a predetermined amount of cement slurry has been injected into the borehole, a cement plug is inserted into the slurry and is flowed through the casing into the hollow member where it comes to rest in the means provided in the cement collar. Since the cement can on longer flow through the hollow member, the pressure builds up until the pressure release mechanism is activated to open the port means located above the collar. Cement slurry fiows through the port means into the restricted passageway means and on to the annular chamber from where it is sprayed out under great force against the borehole walls both above and below the producing formation. The jetting action peels the filter cake and mud from the borehole wall, and the sprayed slurry mixes with the already present slurry which had been flowed through the cement shoe to form a watertight bond in the areas that have been cleared of the mud cake and filter both above and below the producing formation. Since the entire operation is done simultaneously, the cement has an opportunity to set more firmly than if the jetting were first accomplished at one level and then the whole casing lowered or raised a given distance, disturbing the setting cement, to repeat the jetting action to complete sealing off the producing formation. It should be noted that the casing may be rotated in the hole during the jetting action to give a better abrading effect since rotation may be accomplished during the continuous injection of slurry, does not require any time-consuming operations that are attendant a vertical readjustment, and does not interfere with the cement injecting operation. A slight vertical movement which would not disturb the setting cement or require shutoff of the cement slurry flow might be desirable under certain conditions to increase the effect of the abrading action.

The vertical distance between the annular chambers is dependent on the thickness of the formation which is to be isolated. The number, size, and location of the jet ports in each of the annular chambers will be determined by many factors. In the preferred embodiment of the invention the jet ports would be directed so that the stream of cement slurry would leave the annular chamber substantially normal to the center line of the casing. The slurry strikes the borehole wall normal to the center line of the borehole, thus giving a maximum abrading effect. If a particularly resistant filter cake were encountered, it sometimes would be advantageous to incline the jet ports so that the slurry will strike the borehole wall on a slight angle. This is particularly true where the mud cake is susceptible to being peeled from the wall by the action of the jet stream. One application not intended to limit the invention but rather as a guide to what can be expected, wherein cement slurry is injected at a rate of 500 gallons a minute, would allow the spacing of 254 diameter jet ports around the two annular chambers with a resultant jet velocity of 50 feet per second achieved at each jet port. For example, on a pair of 7 diameter annular chambers, these jet ports could be formed in 18 rows on each chamber with 3" centers between ports. The spacing and sizing of the jet ports in each particular case depends on borehole considerations such as the amount of filter cake, the density and A viscosity of the slurry, the type of formation to be bonded, and the diameter of the borehole.

Referring to FIGURE 1, the hollow member 36 is connected at the top to the casing 30 and at the bottom to the cement float shoe 31. The annular chambers 32 are attached to the hollow member 36 both above and below the producing formation 20. Jet ports 61 are located around the circumference of the annular chambers 32. The restricted passageway means 35a, 35b, 35c, 35d, "35c, and 35 interconnect the annular chambers with each other and with the port means 37a, 37b, 37c, 37d, 37e, and 37 in the hollow member 36. The cement collar assembly including sleeve 38, shear pins 39, and seat 40 is located inside of the hollow member near port means 37a, 37b, 37c, 37d, 37e, and 37]. Overlying strata 22 and underlying strata 24 along with producing formation 29 are pierced by borehole 23. Since it is desired to isolate producing formation 20 from water at shale formations 22 and 24, the jet ports 61 are located opposite these formations in order that a watertight seal may be formed by abrading filter cake 26 from borehole wall 23 to give a better bond between the wall and the cement. Cement slurry 33 is being injected into the void between the hollow member 36 and the borehole walls 23 through cement float shoe 12 at ball valve 10. This injection continues until a predetermined volume of cement is injected.

As depicted in FIGURE 2, a cement plug 50, which had been inserted into the cement slurry 33 after a predetermined amount of cement has been injected, has seated in the beveled face of the cement collar sleeve 33; and the increased pressure on shear pins 39 has caused the pins to fail, allowing the sleeve 38 to slide down to cement collar seat 40, thus exposing port means 37a, 37b, 37c, 37d, 37e, and 37 to the cement slurry. The slurry flows through the port means 37a, 37b, 37c, 37d, 37e, and 37] into the restricted passageway means 35a, 35b, 35c, 35a, 35a, and 351 and thence into annular chambers 32 from where it is forced in a jetting action indicated by 21 through jet ports 61 against borehole wall 23 to peel filter cake 26 from the borehole wall.

FIGURE 3 is a section taken from FIGURE 1 at 3-3 showing a view of the restricted passageway means 35a, 35b, 35c, 35d, 35a, and 35f hollow member 36, cement collar sleeve 38, and port means 37a, 37b, 37c, 37d, 37a, and 35).

FIGURE 4 depicts an alternative embodiment of the invention wherein the restricted passageway means 60 is in the form of a concentric shell around the hollow member 36. This construction is desirable under some conditions to obtain a more even flow to the annular chambers 32. Jet ports 62 are narrow vertical slits. The jet ports 62 function in much the same manner as when used with the restricted passageway means used in the preferred embodiment. During the jetting action the drill string can be rotated in the hole so that complete coverage of the interior of the borehole might be obtained.

Section 5-5 is shown in FIGURE 5 wherein the restricted passageway means 60, the hollow member 36, the cement collar sleeve 38, and port means 37a, 37b, 37c, 37d, 37e, and 37 are depicted.

From the foregoing description, it may be seen that the present invention operates simply and in a novel manner to remove filter cake and mud from the wall of a borehole during cementing operations without the necessity of repositioning the tool to completely seal off a producing formation. Although only a few preferred methods and modes of construction have been illustrated and described, those skilled in the art will be able to perceive numerous modifications, variations, and changes in this invention that could be made without departing from the spirit thereof. All such modifications, variations, and changes that could be made in the arrangements, methods, and modes described herein that fall within the scope of the appended claims are intended to be embraced thereby.

The invention having been fully described, I claim:

1. A method of cementing a well casing in a well bore which comprises ejecting a cement slurry from the interior of the casing through the lower end of said casing, flowing said cement slury upwardly through the annular space between said casing and the wall of said well bore to extend from the bottom of said well bore to a position above a potential oil-producing horizon traversed by said well bore, interrupting the flow of cement through the lower end of said well bore, then directing said cement slurry simultaneously along a path both upwardly and downwardly parallel and exterior to said well casing from a location substantially adjacent said producing horizon, then directing said cement slurry radially outward from said casing in a substantially uniform radial pattern around the periphery of said well casing both above and below said potential oil-producing horizon, and applying pressure to said cement slurry sufficient to eject it at a high velocity against the well bore wall to erode the deposited layer of mud cake from the well bore at positions both above and below said potential oilproducing horizon in the presence of the previously positioned cement slurry so that upon abrasion of the mud cake from the well bore wall the previously deposited cement slury in said annular space forms a reservoir and with the jetted slurry uniformly replaces said deposited layer of mud cake with cement to improve the bonding between said casing and the wall of said Well bore above and below said producing horizon.

2. Jet cement apparatus for positioning in a borehole casing string and adapted to be cemented therewith comprising a central hollow member, port means positioned intermediate the ends of said hollow member, means movable for opening said port means to the flow of cement slurry, said means initially positioned on the inside wall of said hollow member closing said port means, passageway means communicating with said port means extending longitudinally along the periphery of said hollow member, a pair of tubular members vertically spaced apart on the periphery of said hollow member to form a pair of annular chambers, said annular chambers communicating with said port means through said passageway means and a plurality of jet ports on the said tubular members, said jet ports so located as to jet cement against the wall of said borehole.

3. The method of cementing a casing in a well comprising the steps of ejecting a cement slurry from the interior of said casing through the lower end of said casing into said well, flowing cement slurry upwardly through the annular space between said casing and the wall of said well to extend from the bottom of said well to a position above a potential oil-producing horizon traversed by said well, interrupting the flow of cement slurry through the lower end of said casing, flowing cement slurry from a position in said casing substantially intermediate said potential oil-producing horizon simultaneously to positions both above and below said potential oil-producing horizon, then directing cement slurry radially outward from both of said positions above and below said potential oil-producing horizon around the periphery of said well casing and applying pressure to said cement slury sufficient to eject it from both of said positions above and below said potential oil-producing horizon at a high velocity against the well wall to erode the deposited layer of mud cake from the well wall both above and below said potential oil-producing horizon in the presence of the previously positioned cement slurry so that upon abrasion of the mud cake from the well wall the previously deposited cement slurry in said annular space forms a reservoir and with the jetted slurry uniformly replaces said deposited layer of mud cake with cement to improve the bonding between said casing and the wall of said well above and below said potential producing horizon.

4. Well cement apparatus adapted to be positioned in a well as a portion of the well casing and to be cemented therein comprising a hollow elongated member, a pair of tubular members secured to the exterior of said elongated member to form annular chambers therewith in vertically separated relationship a preselected distance apart to bridge a desired producing formation, jet ports adapted to direct cement slurry against the wall of said well, said jet ports formed in the outside Wall of said tubular members, a passageway for cement slurry on the exterior of said elongated member, said passageway in communication with said annular chambers, ports in said elongated member for communication between the interior of said hollow member and said passageway, means movable for opening said ports, said means initially positioned on the inside wall of said elongated member closing said ports for flowing cement slurry through said elongated member, and means for moving said movable means to open said ports to the flow of cement slurry.

References Cited in the file of this patent UNITED STATES PATENTS 2,191,750 Brown Feb. 27, 1940 2,196,652 Baker Apr. 9, 1940 2,811,206 Klotz Oct. 29, 1957 2,811,208 Eadie Oct. 29, 1957 

